Pharmacokinetics

Different penicillins vary in their pharmacokinetics. Amoxicillin has a high oral bioavailability, whereas benzylpenicillin (penicillin G) is so poorly absorbed from the GI tract that it is not available as an oral preparation. Most penicillins can be given by either intravenous or intramuscular injection. Penicillins distribute well in the body; however, they will not cross the blood-brain barrier unless the meninges are inflamed. Penicillins are renally excreted and so will require dose modification in patients with impaired renal function.